Left ventricular unloading during extracorporeal membrane oxygenation - Impella versus atrial septal defect: A simulation study.

Background: Atrial septal defect and Impella have been proposed for left ventricular unloading in venoarterial extracorporeal membrane oxygenation patients. This work aims at evaluating the haemodynamic changes in venoarterial extracorporeal membrane oxygenation patients after Impella implantation or atrial septal defect realization by a simulation study. Methods: A lumped parameter model of the cardiovascular system was adapted to this study. Atrial septal defect was modelled as a resistance between the two atria. Venoarterial extracorporeal membrane oxygenation and Impella were modelled starting from their pressure-flow characteristics. The baseline condition of a patient undergoing venoarterial extracorporeal membrane oxygenation was reproduced starting from haemodynamic and echocardiographic data. The effects of different atrial septal defect size, Impella and venoarterial extracorporeal membrane oxygenation support were simulated. Results: Impella caused an increment of mean arterial pressure up to 67%, a decrement in mean pulmonary arterial pressure up to 8%, a decrement in left ventricular end systolic volume up to 11% with a reduction up to 97% of left ventricular cardiac output. Atrial septal defect reduces left atrial pressure (19%), increases right atrial pressure (22%), increases mean arterial pressure (18%), decreases left ventricular end systolic volume (11%), increases right ventricular volume (33%) and decreases left ventricular cardiac output (55%). Conclusion: Impella has a higher capability in left ventricular unloading during venoarterial extracorporeal membrane oxygenation in comparison to atrial septal defect with a lower right ventricular overload.